An approach is described and used to develop a generalized predictive equation for the effect of temperature on the kinematic viscosity of crude oil fractions. The use of this simple method for another crude oil fraction does not require any viscosity measurement; it only requires the mean boiling temperature of the crude oil fraction to predict the single parameter in the viscosity-temperature equation, based on the two-parameter Walther’s viscosity correlation. The approach is illustrated and validated with viscosity data reported in the literature for sixteen crude oil fractions, which are matched with an average deviation of 2.5%.